Recently, the technology is widely available for capturing an image of a two-dimensional code by a camera for recognition and allowing a predetermined process associated with the code data to be performed. Compared to one-dimensional codes, two-dimensional codes can store a larger amount of coded information. Various kinds of two-dimensional codes are available these days. The data for a two-dimensional code needs to be read from image data efficiently and properly. In this background, technologies related to image recognition of two-dimensional codes have been proposed (e.g. patent document 1).    patent document 1            JP 2000-82108        